1. Field of the Invention
The invention relates to a communication system.
2. Description of Related Art
There is known the function of a vehicle, which allows doors of the vehicle to be locked or unlocked and an engine to be started without using a mechanical key. This function is also called smart system.
In the smart system, communication is carried out between a mobile device (key) and an electronic control unit (ECU) or body control module (BCM) mounted on the vehicle. The mobile device that has received a request signal from the vehicle transmits a response signal. The response signal is received by the tuner of the vehicle and is verified by a verification electronic control unit. When communication has been established between the mobile device and the electronic control unit or body control module, it is allowed to lock or unlock the doors and to start the engine.
There is known a radio receiver that detects a current location of a vehicle and automatically sets its receiving specifications to specifications that match an area to which the current location belongs (for example, see Japanese Patent Application Publication No. 2006-333006 (JP 2006-333006 A)).
Tuners that receive radio waves from mobile devices each have a frequency that is set in conformity with the radio law of each country. In addition, performance that is required for each tuner depends on a vehicle model on which an antenna is mounted and a mounting condition of the antenna as well.
Thus, tuners are prepared for each destination area and for each vehicle model and each antenna mounting condition. Therefore, there are significantly many part numbers for tuners. In addition, as in the technique described in JP 2006-333006 A, equipping tuners with the function that the receiving specifications are automatically set on the basis of a current location leads to an increase in product cost.